1. Field of the Invention
The present invention relates to a fixing processing apparatus, an inkjet recording apparatus and a fixing processing method, and more particularly to technology for drying ink and fixing an image after forming an image.
2. Description of the Related Art
Currently, an inkjet recording apparatus which uses water-based ink is desirable for use as a general image recording apparatus. In an inkjet recording apparatus which uses water-based ink, it is desirable to carry out a compulsory drying process by applying heat to a recording medium after forming an image thereon, in order to raise the printing speed. Furthermore, in order to improve the light resistance and wear resistance of the recorded image, it is effective to record an image with a liquid, such as ink, that contains polymer particles, and then carry out processing for forming a film of the polymer particles by applying heat and pressure after the recording of the image.
In order to carry out successful image formation onto media of various types (in particular, coated paper for printing) using an inkjet method, a direct recording method employing an aggregating treatment agent which aggregates the ink has been investigated. In particular, a desirable method is one according to which an image is formed by ejecting and depositing droplets of ink having added polymer particles for fixing, onto a recording medium on the surface of which a layer of aggregating treatment agent has been formed by depositing and then drying an aggregating treatment agent having added polymer particles of latex, or the like, removing the water content from the recording medium after the ink has aggregated, and also fixing the ink to the recording medium while forming a film of the polymer particles, by means of a heating process or pressing process.
It is desirable to use a so-called coated printing paper as the recording medium in an inkjet recording apparatus to be used alternatively to a conventional printing apparatus. In this case, it is necessary to carry out a gloss fixing process over a broad width, in accordance with different paper types, such as art paper, matt-coated paper, gloss-coated paper, gloss-matt-coated paper, fine-coated paper, and the like.
However, it is difficult to carry out a suitable fixing process in a stable fashion, in respect of these differences, simply by adjusting the temperature and pressure alone. In particular, matt-coated paper and fine-coated paper have large indentations in the coating layer and if an aggregating treatment agent is applied with a roller, or the like, a thick layer of the aggregating treatment agent is liable to form and problems are liable to occur due to the aggregating treatment agent permeating into the paper and damaging the coating layer or the interface between the coating layer and the base paper layer, leading to roller offset, and the like, when heat and pressure fixing is then carried out. This is especially marked in cases where the coating layer is thin.
Japanese Patent Application Publication No. 2002-283553 discloses technology for an inkjet recording apparatus which records an image by ejecting and depositing ink onto a recording medium having a resin layer on the surface thereof, wherein the glossiness of the image surface of the recording medium is controlled by controlling at least one of the heating temperature, the applying pressure, the recording medium conveyance speed, and the pressing force, applied to the recording medium. This inkjet recording apparatus is able to change the degree of glossiness by adjusting the fixing temperature, pressure and time; however, in cases where low gloss is required, such as text images or matt-coated paper, the contact with the recording medium is liable to become instable if the pressure is simply reduced. Moreover, if the temperature is simply reduced, then the effects on the drying and permeation of the ink during fixing are also reduced, and the ink fixing properties are liable to decline, whereas if the conveyance speed is raised, then problems such as conveyance errors, or the like, become liable to occur.
Furthermore, in a composition where image formation is carried out after applying aggregating treatment agent to a matt-coated paper or fine-coated paper, the applied amount of aggregating treatment agent is liable to become large due to the indentations in the surface of the recording medium, and therefore problems such as roller offset are liable to occur due to damage to the coating layer and the interface between the coating layer and the base paper layer caused by the permeation of the solvent component of the aggregating treatment agent.
Japanese Patent Application Publication No. 2004-188867 discloses technology for an inkjet recording image forming apparatus which forms an image by ejecting and depositing ink onto a recording medium and promotes drying by heating the ink on the recording medium, wherein, if the type of recording medium is glossy paper, then the heating temperature is set to a low temperature compared to when using normal paper, thereby avoiding adverse effects on the coating layer due to heat, and avoiding the occurrence of image non-uniformities or detachment of the coating layer. When this technology is applied to the gloss processing of coated paper; however, even if a heating temperature lower than the melting point of the resin constituting the coating layer is set universally, it is difficult to adjust the glossiness in accordance with the type of surface of, for instance, matt-coated paper and gloss coated paper.